Solar Energy FAQ
Solar modules (also known as photovoltaic or PV modules) convert solar radiation into electrical energy. Solar cells use daylight to generate a DC output which is stored in a battery bank. This stored energy is converted to AC power (220V/50Hz or 110V/60Hz) by an inverter and fed into the load at the home, factory, office, or farmhouse.
The output of the battery is connected via an inverter which provides AC power (220V/50Hz or 110V/60Hz). This can be connected to the main panelboard of the building or a separate distribution board may be installed that controls the circuits that are to be powered by solar energy.
Any authorised contractor/installer can install the entire electrical system from the modules to the inverter. All electrical connections between the inverter and the load must be made by the client’s electrical contractor.
A photovoltaic system with a nominal output of 1,000 Watt (1 kWp) requires approx. 9 m² of roof surface area. The size of the solar energy system should be adapted to suit the size of the suitable roof area.
Since a solar energy system is specifically designed based on the client's load, as well as other requirements, each system will vary in size, therefore varying in cost.
Photovoltaic systems require almost no maintenance. Consequently the operating and maintenance costs are very low. Dust and dirt are usually washed away by the rain. It is advisable that the user should remove any significant accumulation of dirt from the solar panels, e.g. leaves, dust particles.
A wind-solar energy hybrid system combines a solar module with a wind turbine to generate electricity, while the charge controller, batteries and inverter are common. This allows for a more reliable system since it is dependent on two sources of energy, and the cost is optimised since both of them use the same delivery system (inverter/controller/battery/cables).
Optimum yield is achieved on a south-facing roof with a pitch of 30-45 degrees depending on the latitude. The energy yield will reduce slightly if the roof orientation tends towards the south-east or south-west, or if the pitch is between 25 and 60 degrees. Shadowing effects caused by growing trees, aerials or gables must be avoided as this significantly reduces the power yield.
Normally we would quote for 1-phase systems. However, we can also provide 3-phase systems as well if required. Most industrial applications would require 3-phase loads. However, for home applications, there is not need to use 3-phase systems since almost all loads are 1-phase.
It is not recommended that car batteries be used for solar applications. The best option is to use VRLA – AGM type Deep Cycle batteries, which are sealed and maintenance free. These also allow for longer life (5-8 years) and are able to sustain heavier loads. These VRLA Deep Cycle batteries also allow for discharge up to 60% against 20% for the car batteries.
Sun shines over most parts of Asia throughout the year. The intensity of solar energy is very good. Cloud cover in these parts is no more than 30-60 days per year. Thus, solar energy is a very good proposition.
In most cases, planning permission is not required when installing a photovoltaic system on a roof
Every stand alone solar energy system consists of four parts:
1. Solar Array on the roof or in the open area composed of several electrically interconnected solar modules.
2. Charge Controller, which controls the voltage and charges the battery bank
3. Battery bank for storing the generated electricity.
4. Inverter, which converts the DC output from the battery bank to standard AC mains voltage as well as monitoring the mains supply and performing yield optimisation functions.
A flat roof or a sloping roof is acceptable. However, in case of a sloping roof, the slope should preferably face the south for the regions in the Northern Hemisphere. The solar modules are usually mounted above the roof using special brackets, mounted at an incline depending on the latitude.
The pitch and alignment of the roof does affect the energy yield. Its influence is often overestimated. A solar energy system aligned to the East or West with a roof pitch of 30 degrees will still provide 80% of the maximum output as compared to that which is aligned to the South. The greater the deviation of the surface from the South, the better it is to use a flatter tilt angle. The most important factor is to avoid shadows being cast on the solar modules. There will be a significant detrimental impact if trees, aerial masts, power cables or gabled dormer windows deprive the modules of light.
There are many factors one needs to consider before deciding on the plan for a solar energy installation. The financial benefits of a solar energy system are mainly dependent on the chosen technology and its components. The life of the solar panels, of the batteries and inverter/controller is important. Does one select an expensive, high-performance module? It is also important to ensure that VRLA Deep Cycle Batteries are chosen. The installation company must be qualified? These are among the many questions affecting the profitability of a solar energy system. Our experienced advisors will be pleased to pay you a visit.
This is dependent on the peak installed output and hence the available area for the solar module. Modules using crystalline solar cells generate approximately 1 kilowatt of peak power for an area of 5 to 10 square metres. Optimum alignment is achieved on south-facing roofs with a pitch of 30 degrees. Solar maps provide additional information on the intensity of solar radiation. Apart from the available area, the level of financial investment is another major criterion. Many governments now provide various incentives to try to make solar energy more attractive.
To view solar maps of Pakistan, or other countries around the world, please click here.
The maximum rated output of a photovoltaic device, such as a solar cell or array, under standardized test conditions, usually 1000 watts per square meter (0.645 watts per square inch) of sunlight with other conditions, such as temperature specified. Typical rating conditions are 68°F (20°C), ambient air temperature, and 1 m/s (6.2 x 10-3 miles/sec.) wind speed.
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